package com.baroxtech.anoterecorder;

import android.media.midi.MidiReceiver;
import android.util.Log;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Convert stream of arbitrary MIDI bytes into discrete messages.
 * <p>
 * Parses the incoming bytes and then posts individual messages to the receiver
 * specified in the constructor. Short messages of 1-3 bytes will be complete.
 * System Exclusive messages may be posted in pieces.
 * <p>
 * Resolves Running Status and interleaved System Real-Time messages.
 */
class AMIDICommandReceiver extends MidiReceiver {
    protected final static String TAG = "AMIDICommandReceiver";
    private static final long NANOS_PER_MILLISECOND = 1000000L;
    private byte[] mBuffer = new byte[3];
    private int mCount;
    private byte mRunningStatus;
    private int mNeeded;
    private boolean mInSysEx;
    
    public interface CommandsHandler {
        void onCommands(final List<AMIDICommand> commands);
    }

    private CommandsHandler handler;

    public AMIDICommandReceiver(CommandsHandler handler) {
        this.handler = handler;
    }

    /*
     * @see android.midi.MidiReceiver#onSend(byte[], int, int, long)
     */
    @Override
    public void onSend(byte[] data, int offset, int count, long timestamp)
            throws IOException {
        ArrayList<AMIDICommand> commands = new ArrayList<>();
        int sysExStartOffset = (mInSysEx ? offset : -1);
        for (int i = 0; i < count; i++) {
            final byte currentByte = data[offset];
            final int currentInt = currentByte & 0xFF;
            if (currentInt >= 0x80) { // status byte?
                if (currentInt < 0xF0) { // channel message?
                    mRunningStatus = currentByte;
                    mCount = 1;
                    mNeeded = AMIDIConstants.getBytesPerMessage(currentByte) - 1;
                } else if (currentInt < 0xF8) { // system common?
                    if (currentInt == 0xF0 /* SysEx Start */) {
                        mInSysEx = true;
                        sysExStartOffset = offset;
                    } else if (currentInt == 0xF7 /* SysEx End */) {
                        if (mInSysEx) {
                            packCommands(data, sysExStartOffset, offset - sysExStartOffset + 1, timestamp, commands);
                            mInSysEx = false;
                            sysExStartOffset = -1;
                        }
                    } else {
                        mBuffer[0] = currentByte;
                        mRunningStatus = 0;
                        mCount = 1;
                        mNeeded = AMIDIConstants.getBytesPerMessage(currentByte) - 1;
                    }
                } else { // real-time?
                    // Single byte message interleaved with other data.
                    if (mInSysEx) {
                        packCommands(data, sysExStartOffset, offset - sysExStartOffset, timestamp, commands);
                        sysExStartOffset = offset + 1;
                    }
                    packCommands(data, offset, 1, timestamp, commands);
                }
            } else { // data byte
                if (!mInSysEx) {
                    mBuffer[mCount++] = currentByte;
                    if (--mNeeded == 0) {
                        if (mRunningStatus != 0) {
                            mBuffer[0] = mRunningStatus;
                        }
                        packCommands(mBuffer, 0, mCount, timestamp, commands);
                        mNeeded = AMIDIConstants.getBytesPerMessage(mBuffer[0]) - 1;
                        mCount = 1;
                    }
                }
            }
            ++offset;
        }

        // send any accumulatedSysEx data
        if (sysExStartOffset >= 0 && sysExStartOffset < offset) {
            packCommands(data, sysExStartOffset, offset - sysExStartOffset, timestamp, commands);
        }
        if (!commands.isEmpty() && handler != null) {
            handler.onCommands(commands);
        }
    }

    private void packCommands(byte[] data, int offset, int count, long timestamp, ArrayList<AMIDICommand> commands) {
        AMIDICommand cmd = new AMIDICommand(data, offset, count, timestamp);
        commands.add(cmd);
    }

}
